This application claims the priority of Korean Patent Application No. 10-2003-0080686 filed on Nov. 14, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates generally to a device and method for measuring a supply voltage, and more particularly, to a device and method for measuring the maximum value of a plurality of supply voltages during a burn-in test for a semiconductor device.
2. Description of the Related Art
Various tests may be required in order to verify the performance and reliability of a semiconductor device. These tests may lead to increases in the yield of the production of semiconductor devices. A burn-in test is a test which may determine the performance and/or reliability of a semiconductor device by conventional methods. The burn-in test may be a test wherein stress conditions may be applied to a semiconductor device in order to determine whether the semiconductor device may be likely to become defective at an early stage in a fabrication process of the semiconductor device.
By conventional methods, a semiconductor device may be operated under stress conditions. Examples of stress conditions may include forcing the semiconductor to operate with a high supply voltage and/or a high temperature for an extended period of time. Stress conditions may enable defects in the semiconductor device to be determined.
The burn-in test may aid in detecting and screening out defective semiconductor devices. In the burn-in test, an appropriate burn-in stress voltage may be applied to the semiconductor device as an acceleration factor, which may serve to accelerate the rate at which defects in the semiconductor device are determined. An acceleration factor may be a parameter which affects the rate of defect detection in the semiconductor device. A high operating temperature and/or a burn-in stress voltage may be acceleration factors.
With respect to a semiconductor memory device, a magnitude of a voltage of cell data may be an acceleration factor. When the magnitude of a voltage of cell data is at a first logic level (i.e., a high logic level), the magnitude of the voltage of cell data may be a factor in determining a magnitude of a burn-in stress voltage and/or a duration of the burn-in test.
If the burn-in stress voltage is above a threshold voltage, a supply voltage may increase. This increase to the supply voltage may result in an excessive rise of the voltage level in the semiconductor device.
In recent years, semiconductor devices have been fabricated at increasingly smaller sizes. This has enabled metal oxide semiconductor field effect transistors (MOSFETs), formed within semiconductor memory devices, to be reduced in size. The reduction of size of the MOSFETs has led to lower punch-through voltages and thinner gate oxide layers of the MOSFET. With a lower punch-through voltage, there is an increased risk of a MOSFET not being able to fully contain a voltage.
When a high burn-in stress voltage is applied to a semiconductor device, it may be difficult to determine accurate failure causes for the semiconductor device by conventional methods, which may in turn make it difficult to enhance the yield of the semiconductor device. It may not be possible to determine whether device failures are caused due to degradation of devices, progression of initial defects, a punch-through breakdown, and/or gate oxide rupture occurring when a burn-in stress voltage above a threshold voltage is applied to a MOSFET of a semiconductor device by conventional methods.
Conventional circuits exist for detecting whether a burn-in stress voltage applied to a semiconductor memory device exceeds the threshold voltage.
However, detecting whether the burn-in stress voltage exceeds the threshold voltage may not determine accurate failure causes for the semiconductor device. Even with conventional circuits, it may not be possible to determine whether device failures are caused due to degradation of devices, progression of initial defects, a punch-through breakdown, and/or gate oxide rupture occurring when a burn-in stress voltage above a threshold voltage is applied to a MOSFET of a semiconductor device.